There's a moment about two-thirds of the way into this stage adaptation of Sylvain Chomet's cult animated film when the production sparks into life. One of the cast takes on the role of narrator, explaining what's happening on stage: a grandmother is trying to save her cyclist grandson from the Mafia. This narrator speaks in English with a French accent; it's funny and helpful, especially for those who haven't seen the 2002 film. But it's also a bittersweet interlude, because you can't help thinking what this show, a mix of puppetry and physical theatre, might have been with that narrating thread running throughout.

There is undoubtedly a lot of young talent in FellSwoop Theatre, winners of the National Student Drama festival's emerging artists award last year. But the translation of the animated film to stage flounders from the start, and reminds you how hard it is to do mime and puppetry well. While animation offers boundless possibilities and a magical scale and scope on screen, on stage the tale relies on the traditional skills of storytelling, and the company appears to assume a working knowledge of the film. Without it, there are some bewildering scenes that need much more in the way of signposting. FellSwoop would do well to tackle something with a tauter storyline next time; a director who's not part of the cast might help.

That said, there are glimpses of promise. The live music from Ben Osborn and Tegid Cartwright is warmly evocative, and Clem Garrity's design has some effective, quirky details: old suitcases open out to reveal miniature room sets, a dog is created from a leather case, and there's much inventive work with bike wheels. Josh Bridges plays grandmother Madame Souza with the right mix of quaint and feisty, and the production captures the exhaustion of Tour de France-style cycling well.

But there are too many longueurs that need studding with something dramatic; some parts are about as dramatic as a sunken soufflé, with mime and puppetry that fail to dazzle. The puppet of the young Champion promises much, but you never escape the fact that his handler leans over him. It's a similar problem with Bruno the dog and indeed the production as a whole: you never quite suspend disbelief.